1. Field of the Invention
The present invention generally relates to a lighted heat dissipating panel comprised of embedded light sources providing illumination as desired by a uses; more specifically, the present invention relates in at least one embodiment in which the heat dissipating panel is comprised of sustainable materials such as recycled expanded aluminum embedded in glass-carbon composite and in which the light emitting element is a Light Emitting Diode (LED), or a plurality of LEDs, which are in thermal contact with the light emitting surface whereby heat is transferred from the LEDs to the heat dissipating surface. The LEDs are thus cooled and are able to operate at a higher lumen output and with greater reliability than would otherwise be permitted in a non-cooled condition.
2. Background Art
Illuminated panels, for example illuminated shelving and illuminated panels used in architectural applications, have been used for many years and are generally well known in the relevant arts. Illuminated panels have many uses in architectural settings, merchandising settings, and the like. Such panels have generally depended upon either incandescent light elements or fluorescent light elements as the source of illumination embedded within the panel. However, recent advancements in LED technology have given rise to the production of cost efficient LED light elements that produce enough output power that they may be considered as light elements for architectural uses, area illumination, portable lighting such as flashlights, illuminated shelving applications, pool lighting and virtually any other lighting application that was formerly an incandescent or fluorescent lighting application. Such LED lighting has special benefits such as longevity of the light element itself, control over the spectrum of transmitted light, control over the intensity of the transmitted light, and energy efficiency as compared to the afore mentioned traditional light elements. It is thus desirable that LED light elements be utilized as a light element for illuminated panel applications.
As an example of the old art of illuminated panels based upon legacy lighting systems, see the apparatus disclosed in U.S. Pat. No. 6,364,273 BI which is directed towards merchandise shelving, in which is disclosed a shelf having a light rail extending along a front edge of the shelf which comprises a cover adapted to reflect light onto displayed merchandise while permitting light to pass through selected window portions to illuminate product and pricing information printed on transparent or translucent signage. Signage may also be supported on a sign strip behind the light rails, and along the front edge of the shelfboard. In the preferred embodiment wire management is provided by a raceway formed between a cover support and a backing strip for the fluorescent tube. A receptacle in communication with the wiring within the raceway is adapted to receive a connector from the ballust transformer, so that all permanent wiring for the fluorescent tube is concealed within the raceway. The ballust transformer can be unplugged from the wall receptacle and from the raceway receptacle, to thus completely remove the ballust transformer from the shelf for repair or replacement. The apparatus of U.S. Pat. No. 6,364,273 BI discloses fluorescent lighting.
Other exemplary legacy systems are also disclosed in U.S. Pat. No. 6,283,608 BI (disclosing a light fixture for shelving) and U.S. Pat. No. 6,755,547 B2 (disclosing a transparent panel illuminated by embedded light sources). Some illuminated panels utilizing LED light sources have recently been conceived; see, for example, U.S. Pat. No. 7,201,487 B2 (disclosing a transparent panel primarily for use in refrigerators in which the panel is illuminated from the side by embedded light sources, said panel further comprising prismatic shapes within said panel such that light is directed through the top or bottom surfaces of said panel).
LED light sources are also well known in the art. LEDs are light sources based upon a semiconductor structure, specifically a diode structure, which emit incoherent light (which may be in the ultraviolet, visible, or infrared spectrum) when electrical current is passed through the semiconductor junction. The original uses of LED light sources were in low-power applications such as indicator lights on instrumentation panels and the like. However, recent developments in LED technology have increased the output power and efficiency of LED sources so that it is now feasible to utilize them in traditional lighting applications previously reserved for incandescent, fluorescent, sodium, and similar lighting technologies. Commercially available LED light sources surpassed incandescent light source in terms of efficiency in or around 2002. More recently, LED light sources have become commercially available which exceed fluorescent light sources in efficiency. Fluorescent light sources typically exhibit around 100 lumens per Watt (lm/W) efficiency; however LED light sources have been recently developed which exhibit 130 lm/W, and there are other LED light sources available and currently in development which exhibit even greater efficiency.
As the output power of commercially available LED light sources has continued to improve, it has become necessary to develop methodologies and structures for removing the heat generated by the LED from the LED semiconductor junction. Typical problems caused by heating of the semiconductor junction and surrounding structure are: 1) failures brought on by such occurrences as non-homogenous distribution of the current density over the junction (“current crowding”), which causes a local hot spot in the diode junction leading to early failure due to thermal runaway; 2) nucleation and growth of dislocations in the active region of the diode in which the radiative recombination occurs due to the existence of an existing defect in the semiconductor crystalline structure and which is accelerated by heat; 3) degradation of materials utilized in the LED, such as phosphor, causing loss of efficiency and changes in output color; and 4) electromigration of metal atoms at the metallization layers of the diode causing growth of conductive “whiskers” and early failure. This is not a complete list of the undesired effects brought on by elevated temperatures; it is provided herein simply as a list of exemplary effects.
As an example of an LED that may be used in illuminated panel applications see the LED part number CL-L822 from Citizen Electronics Co, LTD. This surface mount LED is characterized by data sheets providing information for these products at a temperature of 25° C., or approximately room temperature. It is therefore desirable to operate these products and those like them as close to room temperature as possible. A heat conduction/dissipation apparatus is therefore required in such applications in order to remove heat from the LED in an effort to operate the LED as close to the data sheet temperature as practicable.
Attempts have been made to provide structure for removing the heat from the semiconductor junction of an LED. See, for example, U.S. Pat. No. 6,639,356 B2 (disclosing a heat dissipating base for an LED, and which further states the heat problem created by the use of LEDs in various applications, namely that “ . . . Heat generated by LED (sic) becomes the largest drawback in LED manufacturing industry, which causes different malfunctions to the circuitry.” U.S. Pat. No. 6,639,356 B2, col. 1. The invention of U.S. Pat. No. 6,639,356 B2 is an attempt to better conduct the heat away from the LED semiconductor junction so as to overcome the problems created by an overheated junction; namely reduced lifetime and output power. However, the invention of U.S. Pat. No. 6,639,356 B2 is directed to a package LED and simply providing a thermally conductive path out of the LED package. It does nothing to address the larger issue of dissipating heat away from the package.
Furthermore, advances in the availability and quality of enviro-friendly materials, including recycled materials such as recycled metals, for example recycled aluminum, and also including organic based resins, for example soy-based urethane, have now made it not only possible but also economically feasible to produce consumer products that are constructed from sustainable resources and at the same time reduce harmful emissions and reduce the carbon footprint.
Soy-based urethanes, for example, may now be used in place of ester-based resins and other urethanes for manufacture of commercial products. Such soy-based urethanes exhibit increased strength to weight ratio, are fabricated from renewable and sustainable resources, specifically soybean oil, require less or even no glass matt and may result in thinner cross sections in the final product, enable faster processing times and therefore higher throughput in production, and produce no Volatile Organic Compounds (VOC) emissions, specifically harmful styrene, during the production process. Furthermore the use of soybean oil based products is advantageous in that it reduces dependence upon foreign source of oil and petroleum products and serves to help insulate from the volatile and increasing price of such petroleum products.
It is therefore desirable that lighted panels should make use of the currently available LED light source technology due to the significant benefits such light sources provide such as extremely long life, ability to control output power and spectrum, and significant reduction in the amount of electrical energy consumed for comparable light output power as compared to traditional light sources. It is also desirable that such panels be sustainably constructed; in other words, be fabricated from renewable and sustainable resources such as materials that are recycled or organically produced materials, or both, so as to require a minimum of new raw materials and thus preserve limited natural resources. It is also desirable that the materials used in the construction of the product be of a nature to assist reducing the carbon footprint by reducing harmful VOC emissions as compared to material traditionally utilized in the production of commercial products.
However, utilizing LED light sources in illuminated panel applications gives rise to the significant challenge of removing the heat from the LED semiconductor junction and surrounding structure. It is thus desirable, and not currently known in the art, that a sustainably constructed heat dissipating apparatus or combination, preferably, but not necessarily, be fabricated at least in part from recycled materials that are a sustainable resource in order to be environmentally friendly, be lightweight, be physically stable and exhibit stiffness and bend resistance so as to be able to bear weight as shelving and to be utilized in architecture, and be conceived and constructed so as to enable the use of LED light sources in illuminated panel applications. It is also desirable that such an apparatus should not be limited to a flat panel shape; in other words, it is desired that it be moldable to a desired shape including three dimensional shapes, curves, and generally non-linear shapes so as to provide the product designer with a great number of options regarding the size and shape of the apparatus.